U.S. Provisional Application No. 60/901,228, filed Feb. 13, 2007, is incorporated herein by reference in its entirety.
Combines are used all over the world to harvest a good many different crops. A typical combine configuration utilizes a separation or threshing system including one or more rotors partially or fully surrounded by a perforated concave, wherein threshed crop material will fall through the perforations of the concave enroute to a cleaning system operable for separating grain of the threshed crop material from material other than grain (MDG). Often, the region of discharge of this threshed crop material from the separating system is not directly or completely above the cleaning system, and a pan or pans, conveyors, or the like are used for conveying and directing the crop material to the cleaning system. It has been observed that not all types of crops will separate in the same manner, and/or exit the threshing system evenly, and, as a result, the cleaning system may be loaded unevenly, even if an intermediate pan or conveyor system is used between the threshing and cleaning systems. For instance, when viewing a separating system from the front or rear, the threshed crop material may be observed to exit the threshing system more heavily on one side or the other. In other instances, the crop material may exit more or less evenly. This characteristic can also vary for an individual crop, and within a field and during a single crop harvesting session, for a variety of reasons, such as, but not limited to, variances in crop population, yield, moisture content and maturity level. A significant problem that can result from uneven distribution of crop material to the cleaning system is increased grain loss resulting from overloading of regions of the cleaning system sieve or sieves.
A variety of devices and systems have long been used for addressing uneven loading problems, but primarily in the context of those arising from operation of a combine on a side slope. Reference in this regard, Hyman et al., U.S. Pat. No. 4,557,276, issued Dec. 10, 1985 to Sperry Corp. which discloses a four-way leveling mechanism for a combine cleaning apparatus. Reference also in this regard with respect to a grain pan disposed between the threshing system and the cleaning system, Hagerer et al., U.S. Pat. No. 4,875,889, issued Oct. 24, 1989 to Deere & Co. which discloses use of adjustable vanes for compensating for uneven material distribution over a grain pan for delivery of threshed crop material to a cleaning system; and Grobler European Patent No. EP0212183 B1 published Mar. 4, 1987, which discloses a combine harvester including a preparation floor intermediate the threshing system and an upper screen of a cleaning system, wherein the preparation floor and screen are independently pivotable laterally.
An observed shortcoming of the apparatus of U.S. Pat. Nos. 4,557,276 and 4,875,889, is that when used alone, such that system is leveled relative to a side slope on which the combine is located, crop material distribution on one or more regions of the sieve may still be concentrated or heavier, as a function of the crop material flow from the threshing system, and significant grain loss can still occur. The independently tiltable, two section preparation floor of European Patent No. EP0212183 B1, because of the split between the two sections, may not allow adequate distribution of crop material over the entire width thereof, particularly if crop deposition thereon from the threshing system is significantly greater on one of the sections, and if the preparation floor is used for adjusting only for a side hill condition, it may not remedy heavier crop material deposition on one side thereof at all.
In light of the capabilities and limitations of the apparatus discussed above for distributing crop material delivery to a cleaning system of a combine, what is sought is a system and method which allows optimizing this capability for accommodating both uneven threshing system output, and uneven terrain, particularly side slope conditions.